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在水下激光脉位调制(PPM)通信中,脉冲的时域展宽容易导致时隙串扰,进而严重影响通信质量。针对这一问题,对光PPM取样信号最大似然时隙(MLC)解调和最大累加计数样值(MAS)解调进行了改进。并根据激光脉冲水下传输后其能量分布的特点,在MAS解调的基础上,提出最大变权重累加计数(MVA)解调。计算机仿真结果表明,相比MAS解调,MVA解调时能明显改善时隙串扰情况下的PPM信号解调性能,并且对水下光信道的随机性有较好的自适应能力,证明了MVA解调方法的有效性,对水下激光无线通信的应用具有重要的实际意义。
In underwater laser pulse-width modulation (PPM) communication, time-domain broadening of the pulse can easily lead to time-slot crosstalk, which can seriously affect the communication quality. In response to this problem, the maximum likelihood slot (MLC) demodulation and maximum accumulated count sample (MAS) demodulation of the sampled PPM signal are improved. According to the characteristics of energy distribution after underwater laser pulse transmission, the maximum variable weight summation (MVA) demodulation is proposed based on MAS demodulation. Computer simulation results show that, compared with MAS demodulation, MVA demodulation can significantly improve the demodulation performance of PPM signals under time-slot crosstalk, and has better adaptability to the randomness of underwater optical channels. It is proved that MVA The effectiveness of the demodulation method has important practical significance for the application of underwater laser wireless communication.